The invention relates to a packaging means such as a bottle, jar or other similar receptacle and to a sealing ring for said packaging means as well as to a process for manufacturing said sealing ring.
The invention will, in particular, find application in the sphere of manufacturing containing devices for the storage or transportation of objects, products, materials or any substances whatsoever as well as in the sphere of manufacturing sealing rings for such devices.
Furthermore, it will be used in various spheres where it is necessary to preserve products or any substances whatsoever under conditions of vacuum or partial vacuum. One of the principal non-limiting applications is to be found in the alimentary sphere. However, other applications might be envisaged, for instance in the medical sphere.
It has, in fact, been known long since in the alimentary sphere for producing preserves with the aid of packaging means such as bottles, jars or other similar receptacles consisting generally in a container of appropriate form and, inter alia, an articulated lid which is locked by means of a closure system.
Furthermore, it is usual to provide, between the container and the lid, a sealing ring which has two functions. In fact, it fulfils a first function when preparing preserves as such and a second function when the preserve has been opened, with a view to its subsequent preservation.
The seals currently available in commerce are produced by extruding pure natural rubber or filled rubber in a die with a tube corresponding to the profile of the seal. Accordingly, a tubular body is formed, which is then cut according to the required thickness of the seal.
This being the case, the full packaging means is generally sterilized, in order to produce such preserves. This sterilization entails virtually total evacuation of the air remaining within the packaging means, and once the latter has been refrigerated, the lid is firmly applied to the container as a result of the atmospheric pressure.
During the sterilization process, vapour is, in fact, produced inside said packaging means, which, during this phase, is evacuated from the packaging means while entraining the residual air. At the moment of refrigeration, the sealing ring and the closure system prevent the outer ambient air or liquid from returning into the receptacle while the vapour contained in the inner space condenses. One is then faced with an internal pressure inside the packaging means equal to the pressure of saturating vapour at ambient temperature.
This internal pressure can decline to a value of several mm Hg until it is very much lower than the atmospheric pressure. Hence, bearing in mind the dimensions of the packaging means, it is not rare to find that stresses of the order of 50 kg are applied to the sealing ring, these stresses being brought about by the negative pressure prevailing in relation to the ambient air within the packaging means.
The problem is therefore to overcome this force acting upon the seal in order to open the packaging means with a view, for example, of consuming the product contained inside.
To this end it should be noted that after sterilization and refrigeration the closure system can be released without at the same time causing the packaging means to be opened, since the lid is pressed against the container owing to the negative pressure inside.
In order to enable such opening, sealing rings are generally provided with a lug projecting to the outside of said packaging means. This lug can then be gripped and pulled firmly so as to pull the seal towards the outside and thus bring about an abrupt entry of air into the packaging means, with a view to enabling it to be opened.
However, it should also be noted that, in order to carry out this operation, it is necessary to exert a traction force on the lug, which is such that certain users do not manage to open the packaging means and, on occasion, even damage or tear the seal.
In order to alleviate the latter disadvantage, such packaging means have been perfected as regards the system for closing and locking the lid on the container.
In fact, metal wire fittings are known which, on the one hand, surround the body of the container, and, on the other hand, the lid, thus enabling articulation and locking of the two components.
Incidentally, said fitting has at the level of the locking system a closing lever so constructed as to enable it to exert, with the aid of a lever arm, a force on the lid during the opening operation, the purpose being to reduce the manual force required.
Nevertheless, one keeps coming across certain people who do not manage to open the packaging means with the aid of this system, and on occasion the negative pressure within the inner space is such that one causes the lever arm to be bent during the unlocking operation.
In order to facilitate opening of such packaging means, one has, more recently, designed a sealing ring with two separate external lugs separated, at the level of the sealing band, by a zone of lower strength.
Opening of the packaging means is enabled after unlocking the lid by simultaneously pulling at the two lugs, so as to separate one from the other in order to try and tear the seal at the level of its low-strength zone.
However, if the operator happens to tear said seal, it should be noted that the packaging means is in danger of being opened abruptly, so that the operator, having both his hands occupied, no longer controls said packaging means, not without giving rise to certain problems.
Furthermore, the seal having been torn can no longer be used for subsequent preservation of the product after opening.
In short, all these opening techniques entail disadvantages, for in many cases they work imperfectly, require considerable force for opening, frequently make the sealing ring unsuitable for further use, and depend equally on the quality and aging of the material of which the seal is substantially made.